Mycoplasmas, Acholeplasmas, and Ureaplasmas are small prokaryotes, all belonging to the Mollicutes class—a class of
bacteria lacking a cell wall and surrounded by a deformable membrane. Mycoplasmas are contaminants found in
biopharmaceutical, biologic, and mammalian cell culture processes that may infect eukaryotic cells, and, as such, they are less
likely to contaminate small-molecule pharmaceutical processes and products. Mycoplasmas can be associated with
microbiological growth media such as Soybean–Casein Digest Medium (SCDM). Mycoplasmas are easily inactivated by heat
and radiation and are therefore not a concern where process streams are terminally sterilized. However, where sterilizing
filtration is employed, the presence of mycoplasmas must be considered in designing filter validation studies. The small size
(0.15–0.3 µm) and flexibility of the organism allows its passage through the 0.2-µm-rated microporous membrane filters
commonly used to sterilize liquid pharmaceutical process streams.
